Leads for administering cardio electrotherapy (e.g., pacing and/or defibrillation) have tubular bodies with electrodes forming a portion of the circumferential outer surface of the lead and/or a portion of the distal end of the lead. The electrodes are used for sensing, pacing and/or defibrillation. Electrodes for over-the-wire leads come in a variety of shapes including rings, coils, studs/bumps, helical spring tips, etc. Regardless of the shape of the electrode, the electrode must be electrically hardwired to a conductor cable extending through the lead body from the pacemaker and/or defibrillator.
It is clinically advantageous to decrease the size of electrodes to improve trackability over guidewires and to lower sensing, pacing and defibrillation thresholds through higher current densities. For example, with respect to ring electrodes, the length of the ring electrode along the longitudinal length of the lead body is shortened to improve trackability and raise current density.
Conductor cables have typically been electrically hardwired to electrodes via welding the cable directly to the electrode or using a short crimp slug welded to the electrode. These methods of hardwiring a cable to an electrode have several disadvantages. First, the weld zone of the cable and the electrode has a decreased fatigue life. Second, the cable can withstand only a reduced pull force due to the reduced/compressed length of a short crimp slug. Third, the methods increase the complexity of tooling and manufacturing. Fourth, as it is advantageous from a manufacturing perspective to minimize the profile of a cable to electrode attachment to aid assembly, the magnitude of the three preceding disadvantages is increased.
There is a need in the art for an attachment configuration and a method of attachment that facilitates the ease of connection between a cable conductor and a lead electrode. There is also a need in the art for an attachment configuration and a method of attachment that increases the integrity of a connection between a cable conductor and a lead electrode.